Sound-box for talking-machines.



W. OPEL. SOUND BOX FOR TALKING'MACHINES.

APPLICATION FILED MAR. 5. 1915.

Patented June 12, 1917.

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-WALTER OPEL, or LnIrzIe, GERMANY.

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rec ss To all whom it may concern: Beit known that I,- WALTER OPEL, aminzen of Germany, and a, resident of Leipzig,

Saxony, State of Germany, have invented certain new and usefulImprovements in or relating to Sound Boxes for Talking Machines, ofwhich thefollowing is a specification.

In order to increase or to weaken the tone action in talking machinesuse is made in connection with the sound-box of needles of appropriatelygreater or smaller thickness. It is, therefore, necessary to interruptthe playing when an alteration in the tone is to be obtained. Moreover,the exchange of the needles is not only costly but frequently results ininconveniences. 'Experiments have been made with a view to changing thetone action by enlarging or increasing the passage, in the sound tube bymeans of a closing member. The known devices of this kind, however, havethe drawback that the individual oscillations of the closing member re-:sult in disturbing noises while at the same time the adjustment issocomplicated and diflicult that it cannot be efiected during playing.

The object of this invention is to avoid the above defects bycontrolling the clear passage of the sound-box casing with the aid oftwo superposed disks having perforations whlch are adapted to registerwith each other. This is accomplished by making one disk rotatable, thatis to say, this disk is capable of oscillating about an axis so that itsperforation more or less frees that of the other disk as will be moreclearly underthe accompany-- stood from a description of ing drawings,in which Figure 1 is a front view of the improved sound-box,

Fig. 2 is a partial elevation and vertical section thereof, on the linea-b of Fig. I,

' Fig. 3 is a front view of a modified con-' struction.

In the example shown, the casing A of the sound-box has connected to ita socket B which is provided with a box-shaped enlargement O, as bestshown in Fi 2. This enlargement serves as the soun chamber proper of thesound-box. The sound-box itself is closed by a disk D which serves alsoas a carrier of the socket B. The disk D is Specification of LettersPatent.

Patented June 12, ILQIL '3...

Application filed March 5, 1915. Serial No. 12,237.-

provided with perforations E through which the sounds produced by thediaphragm F about an axis G is a second disk H provided withperforations I. The perforations in the disk H and those in the disk Dare so located with regard to one another as to enable the clear passageto be regulated by the rotation of the disk H.

The disk His journaled about a relatively light axis or bolt G. Thisdisk H is easily rotatable on the adjoining face of the disk ]D. Thedisk H consists, by preference, of vulcanized fiber, felt or othermaterial which is not liable to individual vibrations causing disturbingnoises. In order to prevent oscillations of the disk H from beingtransmitted to the disk D, provision may be made also' between the twodisks of a layer 0 of felt or like material. The contact, however,between the two disks may be insured by a weak spring K which is slippedover the axis G.

In this manner, while safeguarding a reliable bearing of the rotary diskH on the stationary disk D, an easy rotation of the disk H and thereby aready variation'of the free passage for the sound is at all timesassured. By introducing through a slot L in the casing C a bent pin Minto the disk H so as to serve as a pointer or indicator, theextent ofthe adjustment of the disk H with regard to the disk I) may readily beread ofi from a dial N on the sound-box. It is, therefore, possible tovary the strength of the tone in talking machines of this kind by merelyadjusting the pointer N on the dial and this may be effected even duringthe playing.

In the constructional example shown in 3, one of the disks is providedwith three perforations E E E of gradually increasing diameter, therebyenabling the strength of the tone to be regulated from the finestpianissimo to the strongest fortissimo.

To this end the second disk is provided withthe disk m mm . In theconstructional forms illustrated the axis G has a central arrangement,but it is obvious that it may have an eccentric'al arrangement particarly in the case in which H is to perform merely an oscillating movementon the disk D.

I claim as my invention: 1. A. sound box for talkingmachines in whichthe regulation of the tone is elfected by superposed perforated disks,comprising the sound box casing with perforated rear wall, a box shapedenlargement provided on the rear wall of the sound box casingand adaptedto house a perforated disk, a central 1 aao eo shaft for said disk"within the box and enlargement, and a spring on said shaft adapt.-

ed to press the perforated disk against the. vperforated rear wall ofthe sound box.

2. A sound box for talking machines, comprising the sound box casingwith perforated rear wall, a box shaped enlargement provided on the rearWall of the sound box casing, a central shaft within said casing andenlargement,.and means on said central shaft for regulating the tone.

Signed at Leipzig; Germany this 11" day of February 1915-.

. WALTER OPEL.

